Free piston fluid pumps



March 14, 1961 J. zuBA'rY FREE PISTON FLUID PUMPS 1 2 sheets-sheet 1 Filed 061;. 15, 1958 ATTORNEY m i I,

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March 14, 1961 J. ZUBATY 2,974,601

FREE PISTON FLUID PUMPS Filed 00T.. 15, 1958 2 Sheets-Sheet 2 I N VEN TOR.

States Patent Oce i 2,974,601 Patented Mar. 14, 1961 PISTON FLUID PUMPS Josepli Zubaty,'Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Dela- Walf? l Files oct. 1s, 195s, ser. No. 767,314

2'Cla`ims. (Cl. 10S-52) 'Ihe object` of the present invention is to provide an improved .pump of simplified construction which is readilyadapted for use while submerged in a fluid to be pumped and `which isof low cost construction.

A feature of thelpresent invention is a free pistonenclosed' within a .pumping cylinder to bring about pump4 ing 'action in cooperationwith the latter, a iixed power piston beinglocatedwithin the free piston and contain-` inglvalvedports for controlling Vthe flow of. uid under pressure to electdoperation independent of the pumping cylinder wall. Another feature is a fluid pump having a free piston-forheiecting the pumping action, the free piston being reiprocable on a stationary conduit acting as.rapistonhrod through which pIeSsure lluid is lconductd undermechanical control vas the power transfer medium'."""" 'Ihese and other important features of the invention will now be described'in detail in the specification and then pointed out more particularly in the appended claims.

In the drawings: i Fig. 1 is a sectional View through Ia portion of a gasoline tankand along the axis of a free piston pumpembodying the principles of the present invention;

lFig. 2 is a sectional view through a fixed piston and other portions of the assembly of Fig. 1, vthe View being drawn to an enlarged scale;

Fig. 3 is a view similar to that of Fig. 2, butwith a Valve plate in a different position;

Fig. 4 is a view of details shown in Fig. 2, the view being drawn to a still larger scale;

iFig. 5 is a view looking in the direction of the arrows 5--5 in Fig. 4; and

i to the conduit 78.

and between the flanges a ring 46 is interposed. The

cylinder portions 36 and 38 are similar in construction in that the closed ends thereof have'inlet and exhaust Valves. The pumping portion 36 has two bosses 50 and given to the ball check assemblies of cylinder portion 38. Couplings 60 and 62 are utilized to connect the outlet valve assemblies 54 to branches -`64 and 66 of a fuel line 68 which in time is arranged to conduct fuel discharged Y by the pump to the engine or other point of use. i

Slidably arranged within the pumping cylinder portions 36 and 38 is a cylindrical free piston 70 having endsclosed by two discs 72 and 74 to define a power cylinder. Two conduits 76 and 78 extend from the bosses 26 and 27, respectively, andthese conduits pass `through twoH openings 80 and 82 made'in the end plates 72.v and 74. A sealing washer 84 is held by suitable means 85 to the end plate 72'to form a tight seal around the conduit 76. is `similarly employed with respect A sealing washer 86 Within the free piston 70 is located a piston 90 which is fixed in position by the supporting conduits`14 and 16'; This piston is composed of two generally cylindrical'cast-` ings 92V and 94 which are held'together by means of four 1 bolts 96.V These two castings define two chambers98 and 100v separated by Ialigned crosswebs 102. Bosses yto fthe. plane of the interface of the two castings 92 andi "94 to present surfaces in which Fig. 6 is a sectional view looking in the direction of the arrows 6-6 in Fig. l and drawn to the same scale as utilized in Figs. 2 and 3. Y

In the drawings, Fig. l illustrates a portion of a gasoline tank 10 which encloses a free piston pump generally indicated at 12. Twovertical conduits 14 and 16 are so connected toV the'tank 10 that'they extend up- Wardly through the bottom of the tank and in spaced i relation along the length of the tank. The upper ends of these conduits 14 and 16 are bent at right angles as at 18 and 20 and carry opposedanges 22 and 24 which are held in sealed relation Vto'hubs 26 Yand 27 by means Y of, couplings 28 and 30. The hubs 26 and 27 are integral with end plates 32 and '34,k respectively, and these end plates form the closed ends of two pumping cylinder portions 36 and 38. The latter bear annularV flanges 40 and 42. which are held together by bolts 44 the heads of thesebolts serve -are formed within the fixed piston to accommodate"-L four ports 104, 106, 108 and '1.10. iIt will be noted that the inner faces of these bosses are slanted with 4respect retainingannular seat members 112. i

pivot shaft v114 is mounted in thewebs 102 Yand carries a valve plate 1|16 which is rectangular and of i such size as to beadapted to engagethe valve `seatlringsf- A tripping mechanism includes a rod u118 journaled-.for-

linear and endwise movement in the castings 92 Yand 94. An opening 120 is formed in the valve plate 116 permitting relative motion of the rod 118 with respect to the valve plate. An annular coil spring 122 is loosely retained close to the opening i120 by means of an annular spring retainer124. The latter is welded as at 125 and 127 to the plate 116. The rod 118 has an enlarged ridge portion 126 which is encircled by the spring l122. The ridge portion has shoulders 129 and '131.

Diametrically opposite from the rod 118 and on the otherside of thepivot shaft 114 is an opening 130 in the plate 116 through which extends a rod 132, the opposite ends of |which are journaled in the castings 92 land 9-4. This rod has fixed to it two stop members 134 and A136 which abut opposite sides of the plate 116 with merely sufficient clearance tov permit relative motion of the plate 116 and the rod 132 as the plate is rotated in either'direction about the pivot shaft :114.

. Surrounding the two castings 92 and 94 isa ring 4140 of suitable material such as synthetic rubber or a plastic which is capable of effecting a two-way lip seal between the inner wall of the free piston 70 and the fixed piston 90.

Bolts 144 and 146 are lixed to the end disc 72 in alignment with the rods 132 and 118, respectively, and as stop meansV as. will further appear. i j

With the parts positioned as shown in Fig. 2, it-will be .understood that pressure udV being introducedV through theconduitsf14 and 76 will pass into the chamber98 and through the port 104 into .the left-hand; end

grooves are "formed for left, as viewed in Fig. 1, and the pressure uid previously admitted to the right of the xed piston 90 would simultaneously be exhausted by way of the port 108, the chamber 100 and the conduits 78 Iand 16. Gasoline previously admitted into the pumping cylinder portion 36 by Way of the left-hand check valve 56 will be forced upwardly through the left-hand check valve 54 to the discharge line 68. At this time the rod 118 will have its shoulder 129 abutting the casting 92.

When the free piston 70 reaches the end of its stroke to the left, the rod 132 will strike the stop bolt 144 and positively break contact of the valve plate 116 with its seats. When the plate 11'6 is thus pried loose, the tripping mechanism comprising the spring 122 and the ridged portion 126 takes over and quickly completes the cycle by a snap-over action to position the valve plate 116 as shown in Fig. 3 and to press the shoulder 131 against the casting 94. When this takes place, the flow of the pressure uid again supplied through the conduit 76 will be reversed in that the fluid will be introduced to the opposite end of the interior of the free piston 70. The coil spring 122 maintains a positive seating of the plate 116 against the port seats as a result of its constricting or squeezing action on the ridge portion 126.

The reciprocation of the free piston continues by virtue of the stop action of two bolts 148 and 149 xed to the disc 74. These bolts act `as do the bolts 144 and 146 at the other end of the stroke. As a result, gasoline from the tank will alternately be drawn into opposite ends of the pump 12 by way of the valves 56 and alternately discharged by way of the valves 54.

I claim:

1. A pump comprising a tixed casing detning a pumping chamber, a reciprocable free piston in said pumping chamber and defining a power cylinder, stop means on each end of said free piston, a power piston in said power cylinder 4and fixed relative to said casing, conduit means connected to said power piston from the exterior of said pumping chamber and slidably engaged with said free piston, ports in said xed piston and oommuni- 4 cating with opposite end zones 'of said power cylinder,

valve means controlling said ports, said conduit means being adapted to supply and exhaust power uid alternately from said end zones by way of said valved ports, mechanism on said xed piston and free of said xed pumping chamber casing Ifor automatically tripping said valve means to effect power actuation of said free piston, the said tripping mechanism including a reciprocable rod with a quick action over-center spring arrangement, and a valve plate pivoted in said fixed power piston and adapted to open and close said ports upon contact of said stop means with said reciprocable rod.

2. A pump comprising a xed casing defining a pumping chamber, a reciprocable free piston in said pumping chamber and defining a power cylinder, stop means on each end of said free piston, a power piston in said power cylinder and xed relative to said casing, conduit means connected to said power piston from the exterior of said pumping chamber and slidably engaged With Vsaid free piston, ports in said fixed piston and communicating with opposite end zones of said power cylinder', valve means controlling said ports, said conduit means being adapted to supply and exhaust power fluid alternately yfrom said end zones by way of said valved ports, mechanism on said fixed piston and free of said ixed pumping chamber casing for automatically tripping said valve means to etr'ect power actuation of said free piston, the said tripping mechanism including a reciprocable rrod with a quick action over-center spring arrangement associated therewith, a valve plate pivoted in said fixed power piston and adapted alternately to open and close'said ports upon contact of said stop means with said reciprocable rod at each end of said free piston, a second -rod reciprocable in said power piston and adapted to contact said stop means for initially unseating said valve plate upon reversal of motion of said free piston.

References Cited in the le of this patent UNITED STATES PATENTS 

